I'm not sure if you fully understand the subject matter in question. EventMachine powers Thin, which is one of the most popular app servers in the wild. It's ex

I'm not sure if you fully understand the subject matter in question. EventMachine powers Thin, which is one of the most popular app servers in the wild. It's extremely easy to hook into EventMachine in Rails, and I encourage you to give it a try if you haven't yet. Even if you're not using Thin, EM can run in a thread and you can use it alongside Rails. As for a source for the "heavy use in production" comment, I suppose I can't provide one off the top of my head. However, if you're a Rubyist you know how often Thin is used in production. For a while, it seemed like every deployment guide suggested the use of Thin cluster to run the app. I'm not sure how you reached the conclusion that Sinatra (and thus, Rack apps, including Rails, in general) is difficult to deploy. We have mod_rails which makes it as easy as setting the apache DocumentRoot to your app. If that's not your cup of tea, it's a simple command to start up a cluster of Thin or Unicorn processes, and it's a few lines of nginx configuration to proxy. Essentially identical to how one would deploy node.js or any web development platform in existence for that matter.